The present invention relates to a process for producing foil or fin stock type material from aluminum alloy.
Generic aluminum alloys for producing foil or fin stock are well known. Such generic alloys are represented by 1100, 7072, or 3003. An alloy similar to 3003 (1.0% Fe, 1.2% Mn) containing about 1% zinc for improved corrosion resistance was developed at Alcoa Laboratories of Aluminum Company of America several years ago. However, this alloy still requires a high preheat temperature on the order of about 1100.degree. F. for optimum formability. This alloy recrystallized readily at temperatures below about 700.degree. F. but produced an alloy having a yield strength only on the order of about 6 ksi.
It has been proposed in U.S. Pat. No. 3,397,444 to produce aluminum foil in light gauge aluminum can stock by rolling aluminum alloys containing 0.6-2.5% iron as the essential alloying element, although small amounts of alloying elements, notably magnesium, manganese, and silicon may be present. The essential alloy is cast in conventional ingot form and is reduced to its final gauge by successive hot rolling and cold rolling operations.
U.S. Pat. No. 3,989,548 discloses a procedure for producing high strength aluminum sheet in which a eutectic or near-eutectic ternary aluminum alloy, such as 8007, is cast under controlled conditions so that the intermetallic phases form into thin rods having a length many times greater than their cross section.
It is an object of the present invention to provide a process for producing a foil or fin stock type material having high levels of strength and formability.
It is a further object of the present invention to provide a light gauge sheet, e.g., approximately 0.003-0.006 inch thick sheet, having high strength and formability.
It is yet another object of the present invention to provide an aluminum alloy material having a yield strength higher than annealed ingot source alloys.
It is another object of the present invention to provide a composition which will avoid coarse primary constituents which can occur in 8007 alloy and degrade formability.
It is yet another object of the present invention to provide a material having a uniform structure which has good appearance and avoids localized coarse grains which degrade performance.